Frit compositions for vitreous enamels



Patented Dec. 4, 1951 FRIT COMPOSITIONS FOR VITREOUS ENAMELS Malcolm D. Beals, Plainfield, and Laurence R.

Blair, New Brunswick, N. J.,

assignors to National Lead Company, New York, N. Y., a corporation of New Jersey No Drawing. Application August 10, 1950, Serial No. 178,754

This invention relates to frit compositions for use in preparing vitreous enamels. More specifically it relates to frit compositions useful in preparing vitreous enamels which mature'at low temperatures.

Many types of frit compositions have been proposed and used in the vitreous enameling industry. Many of the prior art compositions, however, mature at relatively high temperatures, i. e. above 825 C. The development of frit compositions which are capable of producing vitreous enamels which have low maturing temperatures has been the goal in the enamel field for many years. It is particularly desirable to produce frit compositions which are capable of producing vitreous enamels which will mature at a temperature of 825 C. or below, preferably below 725 C. At firing temperatures in excess of 825 C. difflculties are encountered in obtaining kiln construction materials which will hold up or have a long life, which is an essential feature of an economical and satisfactory operation. It is particularly advantageous to produce frit compositions which will mature below 725 0. because most enameling steels undergo a volume change above 725 C. which causes warpage in large enamel sections. If the maturing temperature of the vitreous enamels occurs below 725 C., warpage in the enameling steel would be considerably reduced or substantially eliminated. With such vitreous enamels cheaper grades of sheet steel and lighter gauge steel may be employed. Furthermore, the low maturing temperatures result in more efficient utilization of heat, longer life of kiln construction materials, and less maintenance, thereby reducing the operating costs considerably.

An object of this invention, therefore, is to produce frit compositions which ar capable of forming vitreous enamels which will mature at temperatures below 825 C. A further object'is to produce preferred frit compositions which are capable of forming vitreous enamels which will mature at temperatures below 725 C. These and other objects will become apparent from the following more complete description of the present invention.

In its broadest aspects this invention contemplates forming a frit composition which is capable of forming enamels which will mature between 650 C. and 825 C. comprising oxides of aluminum, boron, phosphorus, alkali metals, and titanium. A preferred embodiment of the present invention is to form a frit composition which is capable of forming a vitreous enamel which will 2 Claims. (Cl. 106-48) mature at a temperature between 650 C'. and 725 C. which contains the same ingredientsmen tioned above.

The frit composition capable of forming-a vitreous enamel maturing below 825 C. comprises the following: 6% to 12% Ti02, 18% to 37% P205, 19% to 39% A1203, 7% to 37% B203, 14%

to 23 alkali metal oxide; the sum of the alkali metal oxide and the P205 equal to 58 to 85 of the sum of the alkali metal oxide, the P205 and the B202; when the B20; is less than 22%, the A1203 must be at least 23%; when the B20: is at least 22%, the P205 must be less than 31%; the alkali metal oxide selected from the group consisting of Na2O and Na20 in combination with K20 and Li20; the K20 in amount to replace up to 60% of the Na20; the H20 in amount to replace up to 20% of the Na20.

The compositions which are capable of'form ing a vitreous enamel which will mature below 725 C. comprise the following: 6% to 12% ;Ti0 18% to 37% P205, 19% to 36% A1203, 1.1%. to 33% B202, 18% to 23% alkali metal oxide; the sum of the alkali metal oxide and the P205 equal-to 62% to 83% -ofthe sumof thealkali metal oxide, the, P205 andtheBzOa; when-the B202 is less than 22%, the A1202 must beat least 23%; when the'B203 isat least 22%, the P205 must be less than 31%; the alkali metal oxide selected from the group consisting of Na20 and Na20 in combination with K20 and'LizO; the K20 in amount to replace up to 30% of the Na20; the Li20 in amount to replace up to 20% of the Na20. v

In order to more fully illustrate the present invention the following examples are presented to illustrate the method by which a frit composition is prepared:

EXAMPLE I Preparation of a frit composition capable of forming a vitreous enamel which will mature below 825 C. I

' The following ingredients were dry blended Preparation of vitreous enamel 100 parts of the minus 200 mesh frit material were intimately mixed with 45' parts of .water containing 0.5 parts NaAlO2 to form a slip. The slip formed was then sprayed on ground coated enameling steel panels to a thickness equal to '30.grams-per.sq. it (dry weight). The. coated panel. was .dried. .at. 110 .C. and then .fired .to mature the enamel. A temperature .of. 775 C. ior.3.-minutes was. required-with this particular .-:composition to;.mature..the enamel. The frit material .had the following composition:

Per Cent Ingredient by Weight EXAMPLE II Rreparation -of, a frat composition capable of forming a oz'treousenamelwhich will mature -.-.bel0w 725C.

'-"The following ingrediments were dry blended toform a mixture.

Parts by Ingredients welght 'NflHLPOiTHzO N N0 Preparation of vitreous enamel 9A slip wasprepared fromithis Irit composition using the procedure described in Example. I and was sprayed .on a steel panel. The coated panel was then fired to mature the enamel. A temperature of 700 C. for 3 minutes was required 4 with this particular composition to mature the enamel. The frit material had the following composition:

Per Cent By the present invention, it is possible to prepare frit compositions from which vitreous enamels may be prepared which will mature at temperatures below 825 C. and preferably below The vitreous enamels produced from these frit compositions possess a uniform and glossy surface which is hard and durable and is resistant to acids. These enamels also possess an exceptionally white color with high opacity which is useful for coating many articles of manufacture.

Whilethis invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto and other modifications and variations may be employed within the scope of the following claims.

We claim:

1. A frit composition capable of forming a vitreous enamel which matures at temperatures between 650 C. and 825 C. which comprises from 6% to 12%Ti02, 18% to 37% P205, 19% to 39% A1203, 7% to 37% B202, 14% to 23% alkali metal oxide; the sum of the alkali metal oxide and the P205 equal to 58% to 85% of the sumof the alkali metal oxide, the P205 and the B203; when the'B202 is less than 22%, the

- A1203I1'1US1'. be at least 23%; when the B202 is at least 22%, the P205 must be less than 31%; the alkalimetal oxide selected from the group consisting of Na20" and Na20 in combination with-K20 and Li20; the K20 in amount to replace up .to 60% of the Na20; the U20 in amount to replace'up to 20% of the NazO.

2. .A frit composition capable of forming a vitreous enamel which matures at temperatures between 650 C. and 725 C. which comprises from 6% to 12% Ti02, 18% to 37% P205, 19% to 36% Al203,,1l% to 33% B203, 18% to 23% alkali metal oxideythe sum of the alkali metal oxide and the P205 equal to 62% to 83% .of the sum of the alkali metal oxide, the P205 and B203; when the B203 is less than 22%, the A1202 must be at least 23%; when the B203 is at least 22%, the P205 must be less than 31%; the alkali metal oxide selected from the group consisting of Na2O and NazO in combination with K20 and H20; the K20 in amount to replace up to 30% of the NazO; the H20 in amount to replace up to 20% of the N920.

MALCOM D. BEALS. -IlAUl'tENCE R. BLAIR.

No references cited. 

1. A FRIT COMPOSITION CAPABLE OF FORMING A VITREOUS ENAMEL WHICH MATURES AT TEMPERATURES BETWEEN 650* C. AND 825* C. WHICH COMPRISES FROM 6% TO 12% TIO2, 18% TO 37% P2O5, 19% TO 39% AL2O3, 7% TO 37% B2O3, 14% TO 23% ALAKLI METAL OXIDE; THE SUM OF THE ALKALI METAL OXIDE AND THE P2O5 EQUAL TO 58% TO 8K% OF THE SUM OF THE ALKALI METAL OXIDE, THE P2O5 AND THE B2O3; WHEN THE B2O3 IS LESS THAN 22%, THE AL2O3 MUST BE AT LEAST 23%; WHEN THE B2O3 IS AT LEAST 22%, THE P2O5 MUST BE LESS THAN 31%; THE ALKALI METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF NA2O AND NA2O IN COMBINATION WITH K2O AND LI2O; THE K2O IN AMOUNT TO REPLACE UP TO 60% OF THE NA2O; THE LI2O IN AMOUNT TO REPLACE UP TO 20% OF THE NA2O. 